A train M leaves Meerut at 5AM and reaches Delhi at 9AM.Another train leaves Delhi at 7AM and reaches Meerut at 10.30AM.What time do the two trains cross each others?

Q.A train M leaves Meerut at 5A.M. and reaches Delhi at 9A.M..Another train leaves Delhi at 7A.M. and reaches Meerut at 10.30A.M..What time do the two trains cross each others?

Solution :
Let the distance between the stations =D km
Then  the speed of train from Meerut side=D/4 km/hr and  the speed of train from Delhi side =2D/7 km/hr
Let, after t hours the Delhi to Merrut train starts ,two trains meet each other then
 After x hours, the distance covered by Delhi to Meerut train =2Dx/7 km ------1
As the train from Meerut side has started 2 hours before ,the distance covered by Meerut to Delhi train is=(x+2)D/4----------2
 From1 and 2,
 (x+2)D/4+2Dx/7 km =D
Then solving the equation ,x=14/15hrs=56 miniutes which corresponds to 7:56A.M.(Ans)